spark plugs for 656

Don656 · Dec 5, 2010

What is the correct spark plug for a Farmall 656 tractor? The local Case-IH dealer recommends and sells Champion D21 spark plugs for this tractor, but the last time I changed plugs in this tractor they were selling AC-87 plugs for it. I looked up a cross reference and the corresponding Champion plug for a AC-87 is a D16. I think the D21 plug is a hotter plug than the D16 and I'm afraid that it may be too hot and damage the engine. Or was the AC-87 plugs the dealer sold me before the wrong plug?

rustred · Dec 5, 2010

all depends on what you are doing with the tractor. working it hard use D16 or just puttin around the yard use D21.

Dellbertt · Dec 5, 2010

I have tractors that have the same set of AC C87 for 10 years and still start easy and run smooth.
In my opinion champion plugs are worthless.

Dell

trencherman · Dec 6, 2010

Used to have a 656 and when putting it under power(discing etc.) it would start to lose power and shut down. Wait a minute and go again for a round or two or maybe not make it across the field. Tried everything(coil,plugs, condensor,wires etc. etc.)to no avail. Talked to shop foreman at IH dealer and said I had the wrong plugs. I was also using D21's. He said use D15yc champions. I took a set home and END of problem. He said the plugs are too hot for heavy work and the engine had pre-igniton. I agree with the other reader that a D21 may be the right plug for lite use.

spark plugs for 656

Don656

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rustred

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Dellbertt

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trencherman

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